First-Principles Analysis of CO2 Complexation in Amine Functionalized Ionic Liquids

As global warming is becoming an increasing concern, the capture of CO₂ from flue gas is becoming an important issue. Amine functionalized ionic liquids are being investigated to capture CO₂. One degree of freedom unique to ionic liquids is the choice to tether the amine functionality to the cation or anion. In order to predict the ability of the functionalized ionic liquids to capture CO₂, various ILs were investigated using ab initio calculations. Gas-phase energetics were obtained and compared to experimental results. Results show that cation-tethered amines have a 2 IL to 1 CO₂ reaction stoichiometry while anion-tethered amines have a 1 IL to 1 CO₂ reaction stoichiometry. An isotherm model for the 1:1 reaction was determined and compared to experimental results. The computational results show a good agreement with experimental values.